Isotope data from amino acids indicate Darwin's ground sloth was not an herbivore.

Fossil sloths are regarded as obligate herbivores for reasons including peculiarities of their craniodental morphology and that all living sloths feed exclusively on plants. We challenge this view based on isotopic analyses of nitrogen of specific amino acids, which show that Darwin's ground sloth Mylodon darwinii was an opportunistic omnivore. This direct evidence of omnivory in an ancient sloth requires reevaluation of the ecological structure of South American Cenozoic mammalian communities, as sloths represented a major component of these ecosystems across the past 34 Myr.

Amino acid δC and δN analyses reveal distinct species-specific patterns of trophic plasticity in a marine symbiosis.

Compound-specific isotope analyses (CSIA) and multivariate "isotope fingerprinting" track biosynthetic sources and reveal trophic interactions in food webs. However, CSIA have not been widely applied in the study of marine symbioses. Here, we exposed a reef coral () in symbiosis with Symbiodiniaceae algae to experimental treatments (autotrophy, mixotrophy, heterotrophy) to test for trophic shifts and amino acid (AA) sources using paired bulk (δC, δN) and AA-CSIA (δC, δN).

Trophic Ecology of the Tropical Pacific Sponge Mycale grandis Inferred from Amino Acid Compound-Specific Isotopic Analyses.

Many sponges host abundant and active microbial communities that may play a role in the uptake of dissolved organic matter (DOM) by the sponge holobiont, although the mechanism of DOM uptake and metabolism is uncertain. Bulk and compound-specific isotopic analysis of whole sponge, isolated sponge cells, and isolated symbiotic microbial cells of the shallow water tropical Pacific sponge Mycale grandis were used to elucidate the trophic relationships between the host sponge and its associated microbial community. δN and δC values of amino acids in M.

Light and temperature control the seasonal distribution of thaumarchaeota in the South Atlantic bight.

Mid-summer peaks in the abundance of Thaumarchaeota and nitrite concentration observed on the Georgia, USA, coast could result from in situ activity or advection of populations from another source. We collected data on the distribution of Thaumarchaeota, ammonia-oxidizing betaproteobacteria (AOB), Nitrospina, environmental variables and rates of ammonia oxidation during six cruises in the South Atlantic Bight (SAB) from April to November 2014. These data were used to examine seasonality of nitrification in offshore waters and to test the hypothesis that the bloom was localized to inshore waters.

Diet of the prehistoric population of Rapa Nui (Easter Island, Chile) shows environmental adaptation and resilience.

Objectives: The Rapa Nui "ecocide" narrative questions whether the prehistoric population caused an avoidable ecological disaster through rapid deforestation and over-exploitation of natural resources. The objective of this study was to characterize prehistoric human diets to shed light on human adaptability and land use in an island environment with limited resources.

Materials And Methods: Materials for this study included human, faunal, and botanical remains from the archaeological sites Anakena and Ahu Tepeu on Rapa Nui, dating from c.

Oxidation of urea-derived nitrogen by thaumarchaeota-dominated marine nitrifying communities.

Urea nitrogen has been proposed to contribute significantly to nitrification by marine thaumarchaeotes. These inferences are based on distributions of thaumarchaeote urease genes rather than activity measurements. We found that ammonia oxidation rates were always higher than oxidation rates of urea-derived N in samples from coastal Georgia, USA (means ± SEM: 382 ± 35 versus 73 ± 24 nmol L  d , Mann-Whitney U-test p < 0.

Contribution of ammonia oxidation to chemoautotrophy in Antarctic coastal waters.

There are few measurements of nitrification in polar regions, yet geochemical evidence suggests that it is significant, and chemoautotrophy supported by nitrification has been suggested as an important contribution to prokaryotic production during the polar winter. This study reports seasonal ammonia oxidation (AO) rates, gene and transcript abundance in continental shelf waters west of the Antarctic Peninsula, where Thaumarchaeota strongly dominate populations of ammonia-oxidizing organisms. Higher AO rates were observed in the late winter surface mixed layer compared with the same water mass sampled during summer (mean±s.